1. Field of the Invention
The present invention relates generally to an embankment wall construction to provide a low maintenance slope surface for erosion control or directing and controlling the flow of water. More particularly the present invention relates to a reinforced wall, slope or water control channel having a slope angle of 30.degree. to 75.degree.. The present invention also relates to a method of constructing the slope or water control channel using precast, mortarless blocks or modular units and an improved block configuration for use in such construction.
2. Description of the Prior Art
Several methods currently exist for constructing water and erosion control channels and reinforcement slopes. One method involves a technology referred to as slope paving. Slope paving involves the pouring of concrete into concrete mold forms which define a base and a pair of sloping sidewalls or pouring low slump concrete directly onto the embankment slope without forms. With slope paving, however, several disadvantages exist. First, the permissible slope of the sidewalls is limited. Slope paving generally attempts to match the sidewall slope with the stable slope of the surrounding soil. This is commonly in the range of about 15.degree. to 25.degree.. Construction at a slope greater than this angle creates a danger of wall collapse. Second, soil which is adjacent to the sloped sidewalls cannot be fully compacted. This often results in undermining and erosion and, in some cases, the possibility of wall collapse. Third, slope paving is limited to the construction of relatively smooth wall surfaces. In some cases, this may preclude someone who may have accidently fallen into the channel from being able to get out safely, without assistance.
A further technique currently used to construct water control channels or reinforcement slope structures involves the use of fabric formed concrete revetment mats or the use of relatively large concrete panels laid directly onto a slope and tied together with cables or the like. However, these have many of the same limitations as slope paving including limited sidewall slope and limited soil compaction adjacent to the sidewall.
A third technique used to construct water control channels or reinforcement slope structures involves the use of rock filled wire baskets which are commonly referred to as gabions. With this technique, rock filled baskets are stacked in a semivertical or batteredback fashion. The wire baskets ordinarily do not employ external anchoring means. Instead, they provide stability principally as a result of gravity (i.e.) the weight of the rocks within the wire baskets. Although this method provides an acceptable and durable face and is reasonably stable, construction of such a wall is labor intensive. Further, this technique requires a large supply of fairly large rocks. Such rocks are not always available, and even when they are, they can be prohibitively expensive. Still further, because of the potential corrosion of the wire baskets, this technique is not entirely maintenance free.
Another method of constructing slopes involves the use of matrices of synthetic geogrid type material in which layers of such material are placed horizontally on excavated portions of the slope. These layers extend rearwardly from the face of the slope and, after the excavation has been backfilled, serve to stabilize the slope. This technique, however, relies on effective compaction of the soil mass. This is difficult to achieve, particularly for steep slopes in the vicinity of the slope face since the soil in that area is not laterally constrained. Further, geogrid reinforced slopes are subject to surface erosion due to the lack of a facing element.
Accordingly, a principle limitation of slope paving and the use of fabric revetment or concrete panels is that they must be laid onto a stable slope. This limits the sidewall slope to less than 30.degree., and more typically to a slope of about 15.degree. to 25.degree.. In the case of a water control channels, this increases the channel width or "footprint" needed to carry a given volume of water flow. Although the use of gabions facilitates walls with steeper slopes, such technique also has limitations as discussed above.
Accordingly, there is a need for a cost efficient reinforcement slope or water control channel construction and a method of making the same which overcomes the above limitations. More specifically, a need exists for an embankment wall having a slope angle greater than 30.degree. and which facilitates improved compacting adjacent to the sidewalls.